The rule of lenity applies in criminal proceedings, while the "rule of narrow construction" applies in immigration proceedings. Each relates to construction of statutory provisions, and applies at different stages of the proceedings.
See Benefit of the Lori Rosenberg, Doubt: The Survival of the Principle of Narrow Construction and its Current Applications, 8 BENDER'S IMMIGR. BULL. 1553 (Oct. 1, 2003).